Butter from yak or cow's milk, a staple of Tibetan food: it is churned with tea and salt into butter tea, which is kneaded with tsampa. On ingredient lists of baked goods, 酥油 can also mean shortening.
酥油 usually refers to Tibetan yak-milk butter, a staple of Tibetan cuisine used in 酥油茶 (butter tea) and temple offerings. In baking recipes it usually means shortening.